In a typical dense wavelength division multiplexing (DWDM) optical communication system, there are multiple (e.g. 80, 88 or 96) channels or wavelengths, with a 50 GHz spacing between two neighbouring channels. The data rate of each channel may be very large, e.g. 100 Gbps, 200 Gbps or even higher. In some applications, finer wavelength granularity is desired, i.e., more channels with reduced data rate.
One problem encountered when using a greater density of channels is cross-talk between channels, because channels are tightly packed to reduce spectral gap to avoid spectrum waste. As such, it would be useful in the industry to find a way to reduce the potential for cross-talk amongst optical channels without sacrificing the overall data rate.